Pirlimycin
Pirlimycin hydrochloride
Also known as: Pirsue · Pirlimycin HCl · U-57930E
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Clinical and subclinical mastitis | Infuse contents of one syringe into each affected quarter | Intramammary | q24h | Repeat after 24 hours. May be repeated daily for up to 8 consecutive days. | 🌎 NA |
- Clinical and subclinical mastitis: Use proper teat end preparation, sanitation, and intramammary infusion technique.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Pirlimycin is a lincosamide antibiotic specifically formulated for intramammary infusion in lactating dairy cattle. It is primarily utilized for the treatment of clinical and subclinical mastitis caused by susceptible gram-positive organisms.
- Key Pathogens: Highly active against Staphylococcus species (including S. aureus, S. epidermidis, S. chromogenes, S. hyicus, S. xylosus), Streptococcus species (S. agalactiae, S. dysgalactiae, S. uberis, S. bovis), and Enterococcus faecalis.
- Clinical Pearl: Unlike some older mastitis formulations, pirlimycin exhibits excellent tissue penetration, allowing it to reach deep-seated infections within the udder parenchyma rather than just remaining in the milk compartment.
Note: Organisms with a MIC of ≤ 2 mcg/mL are considered susceptible, while those with a MIC ≥ 4 mcg/mL are considered resistant.
Mechanism of action
Pirlimycin shares its mechanism of action with other lincosamide antibiotics (such as clindamycin and lincomycin).
- Mechanism: Binds reversibly to the 50S ribosomal subunit of susceptible bacterial RNA.
- Pathway: Inhibits peptidyl transferase → prevents peptide bond formation → interferes with bacterial protein synthesis.
- Activity: Generally considered bacteriostatic, but can be bactericidal at high concentrations against highly susceptible organisms. It is a time-dependent antibiotic.
Safety & warnings
Contraindications
- Known hypersensitivity to lincosamides
Adverse effects
- No adverse effects or udder irritation have been reported at labeled doses
Precautions
Milk from untreated quarters must be disposed of during the withdrawal time, as the drug is absorbed systemically and residues may be detected in milk from untreated quarters. Strict adherence to milk and meat withdrawal times is legally required.
Drug interactions
Potential in vitro antagonism; may compete for the same ribosomal binding site
Potential in vitro antagonism; may compete for the same ribosomal binding site
Monitoring
- Clinical efficacy (resolution of mastitis signs, somatic cell counts)
- Strict adherence to withdrawal periods
Pharmacokinetics
Absorption
Absorbed systemically from the udder following intramammary infusion.
Distribution
Penetrates the udder well and is secreted into the milk of all four quarters. Tissue levels in treated quarters are approximately 2-3 times those found in the extracellular fluid.
Elimination
Secreted into milk; specific elimination pathways not fully detailed in the monograph.
Overdose
No specific data is available regarding acute toxicity or overdosage. If an overdose occurs, monitor for signs of local irritation or systemic gastrointestinal upset, and observe extended withdrawal times.
Available products
Formulations
- Intramammary syringe (50 mg/10 mL)
Veterinary
- Pirlimycin HCl Sterile Solution 50 mg (equiv. to free base) in a 10 mL disposable teat syringe (Pirsue Aqueous Gel)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store syringes at or below 25°C (77°F); protect from freezing.
Client information
Important: Strict adherence to withdrawal times is legally required to prevent antibiotic residues in the human food supply.
- Milk Disposal: Milk from all quarters (even the untreated ones) must be discarded during the withdrawal period. The medication is absorbed into the cow's system and will appear in the milk of untreated quarters.
- Hygiene: Ensure the teat end is thoroughly cleaned and sanitized with an alcohol swab before infusion to prevent introducing new, potentially dangerous bacteria (like yeast or Prototheca) into the udder.
- Administration: Follow the veterinarian's exact instructions for the number of days to treat. Do not stop treatment early just because the milk looks normal.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.